A frequency-addressed plasmonic switch was demonstrated by embedding a uniform gold nanodisk array into dual-frequency liquid crystals (DFLCs). The optical properties of the hybrid system were characterized by extinction spectra of localized surface plasmon resonances (LSPRs). The LSPR peak was tuned using a frequency-dependent electric field. A blueshift was observed for frequencies below 15 kHz, and a 23 nm redshift was observed for frequencies above 15 kHz. The switching time for the system was . This DFLC-based active plasmonic system demonstrates an excellent, reversible, frequency-dependent switching behavior and could be used in future integrated nanophotonic circuits.

A frequency-addressed plasmonic switch was demonstrated by embedding a uniform gold nanodisk array into dual-frequency liquid crystals (DFLCs). The optical properties of the hybrid system were characterized by extinction spectra of localized surface plasmon resonances (LSPRs). The LSPR peak was tuned using a frequency-dependent electric field. A blueshift was observed for frequencies below 15 kHz, and a 23 nm redshift was observed for frequencies above 15 kHz. The switching time for the system was . This DFLC-based active plasmonic system demonstrates an excellent, reversible, frequency-dependent switching behavior and could be used in future integrated nanophotonic circuits.

The authors report on high transverse magnetic (TM)-mode responsivity in a waveguided germaniumSchottky-barriermetal-semiconductor-metalphotodetector on silicon-on-insulator substrate for operating wavelength at 1550 nm. The employed aluminum interdigitated electrodes act as a one-dimensional rectangular grating above the depletion layer. By means of properly designed finger dimensions, surface plasmon polariton resonances can be excited at the interface of metal and silicon interfacial layer due to grating coupling. The resulting strong field intensities reach into active region, enabling high absorption under TM injection. At a voltage of 1 V, the TM-mode photocurrent is measured over three times than that of transverse electric mode, in spite of the relatively larger TM insertion loss in the silicon waveguide.

Oxide-confined quantum-well microcavity vertical-cavity surface-emitting lasers(VCSELs) of three-diameters (aperture size , 2.5, and ) have been fabricated that operate as nearly single-mode lasers at ultralow thresholds , 0.16, and 0.20 mA. Relative spectral intensities are measured at a set higher bias current for the three VCSEL sizes to determine the dependence on mode spacing between the fundamental and second order modes, which at increasing diameter are , 1.6, and 1.0 nm. By studying the side-mode suppression ratio and the optical microwave frequency response of the microcavityVCSELs throughout a spread-out group of modes, we are able to resolve the dependence of signal amplitude and time response on the difference in mode spacing, , higher speed response occurring at larger .

Hole transitions from the heavy-hole to the light-hole band contributing to the response range are reported on detectors. The detectors show a spectral response up to , operating up to a temperature of 330 K where the response is superimposed on the free-carrier response. Two characteristic peaks observed between are in good agreement with corresponding energy separations of the and bands and thus originated from transitions. Results will be useful for designing multi-spectral detection which could be realized on a single structure.

We investigate the emission dynamics of InAs/GaAs quantum dots(QDs) coupled to an InGaAsquantum well in a tunnel injection scheme by means of time-resolvedphotoluminescence. Under high-power excitation we observe a redshift in the QD emission of the order of 20 meV. The optical transition intensity shows a complex evolution, where an initial plateau phase is followed by an increase in intensity before a single-exponential decay. We attribute this behavior to the Coulomb interactions between the carriers in a chargedQD and corroborate the experimental results with both a rate equation model and self-consistent eight-band calculations.

We demonstrate that the presence of a supporting substrate can break the symmetry of a metamaterial structure, changing the symmetry of its effective parameters, and giving rise to bianisotropy. This indicates that magnetoelectric coupling will occur in all metamaterials fabricated on a substrate, including those with symmetric designs.

Through the use of high-speed camera and Langmuir probe measurements in a cylindrical Hall thruster, we report the discovery of a rotating spoke of increased plasma density and light emission which correlates with increased electron transport across the magnetic field. As cathodeelectron emission is increased, a sharp transition occurs where the spoke disappears and electron transport decreases. This suggests that a significant fraction of the electron current might be directed through the spoke.

In the present study, electron-beam generation by open discharges was examined. The study was performed at gas pressures up to 20 Torr, and covered all inert gases. At voltages up to 8 kV, electron-beam currents up to 1600 A with current density and a beam generation efficiency in excess of 93% were obtained. The production of electrons from cold cathode was concluded to be of photoemissive nature, enabling the production of high-intensity electron beams in any noble gas or in a mixture of a noble gas with molecular gases irrespective of cathode material.

The structural origin of the high glass-forming ability(GFA) in Gd-doped CuZrAl bulk metallic glasses was investigated via synchrotron radiation techniques combined with simulations. It is found that Gd addition increases and stabilizes the solute-centered clusters, which leads to the relatively high atomic- and cluster-level packing efficiency and GFA in alloy. However, the presence of Al–Gd solute-solute bonding in decreases the packing efficiency, deteriorating the GFA of this alloy. These findings may extend our understanding on the sensitive dependence of GFA on the concentration of doping atoms in a number of multicomponent bulk metallic glasses.

We report the compositional dependence of the electronic band structure for a range of III–V alloys. Standard density functional theory is insufficient to mimic the electronic gap energies at different symmetry points of the Brillouin zone. The Heyd–Scuseria–Ernzerhof hybrid functional with screened exchange accurately reproduces the experimental band gaps and, more importantly, the alloy concentration of the direct-indirect gap crossovers for the III–V alloys studied here: AlGaAs, InAlAs, AlInP, InGaP, and GaAsP.

Strong enhancement of optical quality in quantum wells by incorporating nitrogen in metamorphic InGaAs buffers grown on GaAs substrates is demonstrated. This has resulted in 3.7 or 5.4 times enhancement of photoluminescence intensity from the metamorphic quantum wells when using dilute nitride superlattice alone or adding nitrogen in a strain compensated superlattice, respectively. This study shows great potentials by incorporating N in metamorphic buffers to further improve the quality of metamorphic optoelectronic devices.

A mechanically exfoliated graphene flake on a silicon wafer with 98 nm silicon dioxide on top was scanned with a spectroscopicellipsometer with a focused spot at an angle of 55°. The spectroscopic ellipsometric data were analyzed with an optical model in which the optical constants were parameterized by B-splines. This parameterization is the key for the simultaneous accurate determination of the optical constants in the wavelength range 210–1000 nm and the thickness of graphene, which was found to be 3.4 Å.

The excitonic optical transition energies of single wall carbon nanotubes, that are modified by surrounding materials around the tubes (known as the environmental effect), can be reproduced by defining a dielectric constant which depends on the subband index, nanotube diameter, and exciton size. The environmental effects on excitons can be recognized on a plot of the functional form of simply by the different linear slopes obtained for different samples. This treatment should be very useful for calculating for any type of nanotube environment, hence providing an accurate assignment of many nanotubechiralities.

The authors calculate and analyze intersubband absorption in InAs/GaAs quantum dash ensemble. The absorptionspectrum dominantly occupies the mid- and extends to the far-infrared region. As far as the wetting layer is taken into account, the electron concentration significantly affects the absorption and the spectrum can be tailored by adjusting spacer layers. It is shown that size fluctuation of dashes causes spectrum broadening and its asymmetry, while the increase in the wetting layer thickness leads to a redshift in the spectrum and decrease in the absorption.

Hydrogen related local vibrational modes (LVMs) of ZnO nanoparticles have been studied using Fourier transform infrared spectroscopy and Raman spectroscopy in as prepared and high temperature annealed samples. The obtained experimental results confirm the presence of cationic vacancies in addition to unintentional hydrogen doping and their complex defects such as and . After high temperature annealing, hydrogen related LVMs and multiphonon modes disappear. The presence of these complex defects determines the nonradiative and multiphonon recombination processes in the band gap of ZnO due to carrier trapping at deep levels.

A micropump based on a pair of liquid marbles coated with various powders and connected with a capillary tube is presented. The idea of the micropump is based on the difference of the Laplace pressures in the marbles. The initial stream was supported by the pressure instability developed under wateroverflow. The reported experiments validate the concept of the effective surface tension of liquid marbles. The micropump could be used for precise delivery of small quantities of liquids, the design of microreactors and microfluidics applications.

We report a Raman scattering determination of the energy difference between the conduction-band minimum and the valley minima in -type lattice matched to GaSb. A frequency downshift in the phonon–plasmon coupled mode is observed between 80 K and room temperature that is attributed to electron transfer from the to the valleys. We use the frequency shift to evaluate by performing Lindhard–Mermin line-shape fits for different values. The value increases with electron concentration due to band gaprenormalization. A value is derived for intrinsic material.

Deformation in the phase (R-phase) of NiTiFe was investigated by in situneutron diffraction during compressive loading at cryogenic temperatures. At 216 K, upon loading the R-phase detwinned and subsequently underwent a reversible stress-induced transformation to the phase (martensite). At 92 K on the other hand, detwinning was suppressed and the stress-induced martensite formed did not transform back upon unloading. The experiments also directly observed a hitherto theoretically predicted phase. Rietveld refinement of the neutron diffraction spectra were used to determine lattice parameters of the and R-phases. Plane-specific elastic moduli were also determined for the R-phase.

thin films were deposited on quartz substrates by pulsed laser deposition and postannealed at different temperatures in oxygen ambience. X-ray diffraction, Hall measurement, and x-ray photoelectron spectroscopy were employed to investigate the properties of the annealedthin films. An anomalous electrical transport behavior as a function of the annealing temperature was observed. Both the growth of the crystal grain and oxygen vacancy density variation in the annealing process have been identified to be responsible for the transition of electrical transport properties.